Runflat device and fitting method

ABSTRACT

A runflat device, and a method of fitting a runflat device. The runflat device can include a chain of segments which is flexible enough to be manipulated for fitting, while also being laterally stable to ensure correct positioning and to avoid misalignment when tightening onto a wheel. The fitting method initially expands the runflat device within the cavity of the tyre, retaining the runflat device securely in place against the inside of the tyre&#39;s tread area. This advantageously leaves the beads of the tyre unobstructed for fitting to a wheel.

The invention relates to an improved runflat insert device, and to animproved method of fitting a runflat insert device. Particularly, butnot exclusively, the invention relates to a combined runflat insert anddouble-sided beadlock, and a method of fitting said combined runflatinsert and double-sided beadlock within a single-piece drop centre wheeland tyre assembly.

Puncture or deflation of a pneumatic tyre on a vehicle can lead to aloss of support and stability which can render a vehicle un-driveable.Devices that are fixed to a wheel inside a pneumatic tyre cavity tosupport a deflated tyre are variously known as runflat insert devices.These devices are typically designed and located within the wheel andtyre assembly so that a part of the device rests in the drop-centre or‘well’ of the wheel to support the runflat insert device in use.

As well as a loss of support and stability for the vehicle, a tyredeflation whilst a vehicle is in motion can lead to the tyre's beadsmoving inwards from the wheel rim's seats, resulting in a loss of gripbetween the wheel rim and the tyre and allowing the tyre to rotatearound the wheel rim. Because the tyre is loose on the rim, traction andbraking may be compromised and in extreme cases the tyre may begin toflail or even break up. To overcome these problems, it may be desirableto fit the wheel and tyre assembly with a form of beadlock device.

Beadlock devices are devices which are designed to retain a tyre inposition on a wheel, typically by applying a force to the tyre's beadsto prevent them from slipping against the wheel rim. Beadlock devicesare commonly of an annular construction, and are fitted between thetyre's beads within some two-piece or multi-piece wheel rims where thewheel rims may be forced together under pressure when forming thecomplete wheel in order for the beadlock device to force the tyre'sbeads into the wheel seats. This provides what is commonly termed‘beadlock’, as the lateral force acts on the tyre's beads forcing themhard against the wheel rim's seats or flanges. This effectively locksthe tyre's beads in place so they cannot slip on the wheelcircumferentially when the vehicle is running in deflated (runflat)situations as described above, or in high torque situations (in hightorque situations, typically on heavy vehicles using low gear ratios, atyre may slip and rotate circumferentially around the wheel rim evenwhile the tyre is fully inflated). Clearly this method of beadlockcannot be used on a single-piece drop-centre wheel rim, because there isno way to force the rims of these types of wheels together.

Other devices are available which are simply fitted within the tyrecavity on any conventional wheel (which may be of two-piece,multi-piece, or single-piece drop-centre type) between the tyre's beadsto prevent the beads from slipping inwards. Devices of this style ofconstruction act as bead blocking devices, but cannot provide theindustry with the mechanical characteristics they expect of a beadlockbecause little or no lateral force is applied to the tyre's beads tolock them into the wheel's seats and flanges. If such a bead blockingdevice is combined with a runflat insert it may provide a support forthe deflated tyre to run on whilst preventing the beads from movinginwards on the wheel rim. However, to provide true beadlock in order toprevent a tyre from slipping or rotating around the wheel rim whilerunning inflated or deflated, pressure must be applied to the inside ofboth beads to force them laterally outwards against the wheel rim'sseats and the inner sides of the wheel's flanges, as may be achievedwhen a beadlock device is fitted to the two-piece or multi-piece wheelrim. It can be seen in current applications that even air pressurewithin an inflated tyre cavity may provide insufficient force to preventtyre slippage in high torque situations, so a fairly considerablelateral force is required in some applications to preventcircumferential tyre to wheel slippage.

It is an object of the present invention to provide a combined runflatinsert and double-sided beadlock that can be used on a single-piecedrop-centre wheel.

To provide true beadlock within a single-piece drop-centre wheel rim therunflat and combined beadlock device must have a mechanism to provideadequate lateral pressure against both beads of the tyre after thedevice has been located on the wheel rim and between both beads of thetyre.

Combined runflat insert and bead blocking or beadlock devices requirethat the bead blocking or beadlock components of the device to locatecorrectly and equally around the circumference of the wheel rim andequally between both beads of the tyre before being tightened on to thewheel rim. If such devices are to be tightened from outside the wheelrim and tyre assembly, a normal tyre fitter will be unable to tell, fromoutside the tyre cavity, whether or not a runflat device and itscomponents are located securely in the correct position. As such, amethod of construction and/or assembly must be devised so that this isachieved automatically when the device is tightened during fitting.

Accordingly, it is a further object of the present invention to providea runflat insert and a method of fitting a runflat insert that ensurescorrect seating of the runflat insert on the wheel within the tyre.

The method should prevent components, segments, sections or the completerunflat insert from catching on one side of the inner wall of the tyreor a bead of the tyre that may tip, skew, dislocate or misalign thedevice in such a way that it is not located precisely between the tyre'sbeads when being fitted and when finally tightened.

According to the present invention there is provided a runflat deviceaccording to the appended claim 1.

A further aspect of the present invention provides a runflat deviceaccording to the appended claim 3.

A further aspect of the present invention provides a method of fitting arunflat device according to the appended claim 18.

Further preferred features of the invention are recited in theassociated dependent claims.

A runflat device according to the present invention comprises a flexiblebody with two ends which are joined together by adjustable connectionmeans to form a ring with an adjustable diameter. The adjustableconnection means allow the distance between the ends of the flexiblebody to be adjusted, and comprises one or more rigid elements such thatdiameter of the ring can be forcibly increased by adjusting theconnection means. This allows the runflat device to be forced againstthe inner wall of a tyre and retained in this position while the tyre isfitted to a wheel. The body should be flexible in a first direction toallow for manipulation during fitting, but is preferably substantiallyrigid in a second direction, perpendicular to the first direction, toensure that the body remains aligned during fitting of the runflatdevice.

The body may formed as a chain of individual segments joined together inabutment with one another.

An alternative runflat device according to the present inventioncomprises a body formed as a chain of individual segments joinedtogether in abutment with one another. The chain is flexible in a firstdirection and the ends of the chain are joined together by adjustableconnection means, which can adjust the distance between the ends of thechain, to form a ring with an adjustable diameter.

Having segments joined together in abutment with each other avoidsindividual segments in the chain moving out of alignment as the runflatdevice is tightened onto a wheel. The segments are preferably pre-formedcomponents, preferably of a plastics material. The chain may bearticulated, and remains flexible in a first direction to allow formanipulation during fitting. Preferably, the chain of segments issubstantially inflexible in a second direction, perpendicular to thefirst direction, to ensure that the chain of segments remains alignedduring fitting of the runflat device.

The connection means may comprise one or more rigid elements such thatdiameter of the ring can be forcibly increased by adjusting theconnection means, allowing the runflat device to be forced against theinner wall of a tyre and retained in this position while the tyre isfitted to a wheel.

Where a chain of segments is provided, the segments in the chain may beheld together and pre-tensioned by tensioning means, for example by oneor more cables. The one or more cables may run through guide meansprovided on the segments making up the chain. The guide means may beprovided as separate components fixable to the segments, for examplescrew in eye-bolts, or as integral parts of the segments, for examplemoulded features such as hangers.

The connection means may provided on a separate component which isincorporated into the ring. Where a chain of segments is used, theconnection means may be provided on a further segment which isincorporated into the ring. The further segment may be similar to thesegments making up the chain for ease of manufacture. Indeed, all of thepre-formed segments in the runflat device may be identical inconstruction.

A connector may be provided at each end of the body for receiving a partof the adjustable connection means. The connectors and connection meansmay comprise threaded portions, for example the connectors couldcomprise threaded nuts for receiving threaded rods provided in theadjustable connection means. Preferably, the connection means comprisesa gearbox connected to rotatable threaded rods via universal joints. Theor each connector may be pivotable relative to the body of the runflatdevice to account for changes in the angle of the received part, e.g.the threaded rods, of the adjustable connection means.

The runflat device may further comprise an outer sleeve, which fitsaround a part of the body and is rotatable with respect to the body. Inuse, the sleeve can rotate relative to the body of the runflat device toreduce friction between a deflated tyre and the body of the runflatdevice. By fitting round a part of a runflat body made up of a chain ofsegments, the sleeve also helps to retain the segments in a ring shape.The sleeve may be constructed to help prevent twisting or dislocation ofthe segments to ensure that the chain of segments remains aligned duringfitting of the runflat device.

The runflat device described above, or a similar runflat devicecomprising a flexible body with two ends, can be fitted according to theinvention by the following method:

-   -   coiling the flexible body to a diameter smaller than the        interior diameter of a tyre;    -   inserting the coiled body into the tyre cavity;    -   uncoiling the body within the tyre cavity and connecting the        ends of the body with an adjustable connection means to form a        ring; and    -   expanding the ring with the adjustable connection means to        locate the ring against the inside of the tyre.

The method allows the runflat device to be held in place at the outsidediameter of the tyre cavity, leaving the beads of the tyre unobstructedfor fitting to a wheel.

The method may further comprise the step of fitting an outer sleeve tothe flexible body before coiling the flexible body.

The steps above are performed before fitting the tyre to the wheel.After fitting the device to a wheel, the adjustable connector device maythen be tightened to tighten the ring and locate the runflat device onthe wheel rim in abutment with the beads of the tyre. The adjustableconnection means may be positioned adjacent a valve hole provided in thewheel such that the adjustable connection means can be accessed via thevalve hole for adjusting the diameter of the ring. After tightening therunflat device into place, the method may then comprise the additionalstep of further tightening the adjustable connection means to deform theflexible body. This acts to force parts of the segments against thebeads of the tyre, locking them to the wheel rim.

A better understanding of the present invention will be obtained fromthe following detailed description. The description is given by way ofexample only and makes reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a runflat insert device according to thepresent invention;

FIG. 2 is a perspective view of a section of the runflat insert deviceof FIG. 1;

FIG. 3 is a perspective view of one end of the section shown in FIG. 2;

FIG. 4 is a perspective view of a bracket receiving the cables at oneend of the runflat insert device;

FIG. 5 is a perspective view of a gearbox assembly and threaded rodswhich form the connection between two ends of the runflat insert device;

FIG. 6 is a perspective view of the connection between two ends of therunflat insert device;

FIGS. 7 and 8 are schematic views of the runflat insert device beinginstalled within a tyre cavity;

FIG. 9 is a perspective view of a section of the runflat insert devicearranged ready for tightening onto a wheel; and

FIG. 10 is a detail view of the connection between two ends of therunflat insert device arranged as in FIG. 9.

FIG. 1 shows a runflat insert device 2 (a runflat) comprising a chain ofindividual segments 4 connected together by cables 6. The two ends ofthe chain of segments 4 are then joined together to form a ring as shownin FIG. 1 which, in use, locates within a tyre and rests on the wheel ofa vehicle. Each of the individual segments 4 is formed of a plasticsmaterial and all of the segments 4 used in the runflat 2 have a commondesign, as will become clear from the subsequent Figures.

FIG. 1 also shows an outer annular section or friction roller in theform of a sleeve 8 located around the outside of the runflat 2. Thesleeve 8 is free to rotate relative to the segments 4 around thecircumference of the runflat 2 to provide an anti-friction devicebetween the inside of the tyre tread and the main body of the runflatdevice 2. The sleeve 8 may be formed from a dissimilar material to thatused for the segments 4 to reduce friction between the components,preferably from a different plastics material. Lubrication may also beintroduced between the segments 4 and the sleeve 8 to reduce frictionfurther. The sleeve 8 is a single component that slides onto the tops ofthe segments 4 before the ends of the chain of segments 4 are connectedtogether. It is flexible along its length, to conform to the circularshape of the runflat device, but is relatively rigid laterally.

As well as providing an anti-friction device and improving the lateralstability of the runflat 2, the sleeve 8 also assists in maintainingalignment of the runflat device 2 during fitting, and also helps todistribute forces applied to the device during use, such as from kerbstrikes, to minimise the likelihood of damaging an individual segment 4.The sleeve 8 is simple in construction and lighter in weight than knownroller devices from known runflat devices, which are often built intothe runflat device and incorporate bearings or other moving componentparts. This not only minimises the overall weight of the runflat device2, but also, significantly, minimises the weight of components that movewithin the flat tyre.

The chain of segments 4 that make up the runflat 2 are joined andtightened together by the cables 6 before the runflat 2 is fitted so thedevice comprises a single unit, flexible circumferentially butrigid/inflexible laterally. Some known runflat devices comprise a numberof individual segments that are ‘drawn together’ as the runflat deviceis pulled into place during fitting (for example WO2004/069564). Thismethod has been found to be essentially unusable in practice because itproved almost impossible to pull the individual parts/segments securelyinto place within the tyre's beads without one or more of theparts/segments catching on the side of the tyre's inner wall, or thetyre's bead, on one side or the other. This prevents the runflat devicefrom seating correctly, causing the device either to come loose inservice or fail if run flat. Furthermore, because this misalignment andincorrect seating occurs within the tyre, it is impossible for thefitter to see whether or not the device was seated correctly afterfitting, reducing the chances of incorrect fitting being detected andremedied.

The runflat 2 of the present invention is very stable, almost rigid,laterally, and the individual segments 4 are held tightly together priorto fitting. This greatly simplifies the fitting process and avoids theproblems of misalignment and of segments catching on the tyre asmentioned above.

A section of the runflat device 2, with the outer sleeve 8 removed, isshown in greater detail in FIG. 2. Seven individual segments 4 are shownjoined together by a pair of cables 6. Each segment has acantilever-like cross-section with a generally flat top plate 10 and apair of angled side portions, or legs 12, extending from an underside ofthe top plate 10. In use, the ends 14 of the legs 12 will rest on thewheel of a vehicle abutting the beads of a tyre. The runflat 2 is thussupported across the width of a wheel without extending into the wheelwell. The top plates 10 of a string or chain of segments together makeup the outer diameter of the runflat 2 on which the vehicle will rest inthe event of a deflation of the tyre. The sides 16 of each top plateextend beyond the top of the legs 12 on both sides of each segment 4 toprovide a greater width to the runflat 2 and to provide lips to retainthe edges of the sleeve 8.

Small eye bolts 18 are fitted in holes 20 provided in the underside ofeach segment 4 to carry the cables 6. Two eye bolt holes 20 are providedin each segment, one at either side of the segment 4 at the midpoint ofits length. Four further holes 22 are arranged in a generally squareconfiguration at the centre of the underside of each segment 4.

Each segment 4 in the chain shown is hinged in relation to the nextsegment 4 with typical ‘ball and socket’ construction. This can be seenfrom the segments 4 at the two ends of the chain shown in FIG. 2 wherethe ‘ball’ components 24 are provided on the legs one end of thesegments, and the ‘socket’ components 26 at the other. The balls 24 andsockets 26 are located approximately half way up the legs 12 of thesegments 4, and the legs 12 are angled slightly away from the ball andsocket joint towards the top plate 10 and the end 14 of each leg 12.This angle ensures that that sufficient ‘flex’ between segments 4 isprovided so that a string or chain of segments 4, once connected andtensioned together, may be coiled into a diameter which is less than theinner diameter of the tyre (at its beads) so that it can be easilyinserted into the tyre cavity before fitting the tyre to the wheel rim,and may also be opened up to the largest diameter tyre circumferencerequired.

To ensure that the increase and decrease of diameter of a chain ofsegments 4 does not alter the tension in the cables 6, the cables 6should be located on the centre line circumference of the segments andthe hinge or ball and socket joints 24,26. This is achieved by correctpositioning and size of the eye bolts 20 used to guide the cables 6.

With correct positioning of the tension cables 6, a string ofinter-connected segments 4 may be flexed circumferentially withoutaltering the tension on the cables 6. This allows the segments 4 and the‘ball and socket’ joints 24,26 to be held tightly together bypre-tensioning the cables before the runflat 2 is fitted into a tyrecavity. This prevents dislocation of the individual segments 4 duringfitting and ensures the runflat device 2 is laterally rigid. Thislateral rigidity ensures the complete runflat insert device 2 can onlypull down in one piece and into the correct location between the tyre'sbeads. The sleeve 8 shown in FIG. 1 also further increases the lateralrigidity of the runflat device 2, further assisting in correct locationwhile fitting but retaining the circumferential flexibility necessary.

FIG. 3 shows one end of the chain of segments 4 that will make up thebody of the runflat device 2. The eye of the eye bolts 28 fixed to thelast segment 4 in the chain is threaded to take a hollow adjuster screw30 fitted in the threaded eye. Adjuster screws 30 may be replaced in analternative embodiment by any commonly available cable tensioner. Thecables 6 are terminated here and the threaded adjusters 30 may be turnedto apply the appropriate tension on the cables 6 to firmly hold thestring of segments 4 together.

The ends of the tension cables 6 are fixed to a compensating bracket 32comprising a typical barrel nut 34 for receiving the threaded end of atension rod 44 (see FIG. 5) which is used to tighten the runflat device2 onto a wheel. The compensating bracket 32 allows the tension rod 44 topull the cables 6 with an equalising tension. FIG. 3 also shows anoptional guide channel 36 for receiving and guiding the end of thetension rod 44 during tightening of the runflat device 2. The guidechannel 36 is attached between two adjacent segments 4 using two of thefour central holes 22 from each segment 4.

The bracket 32 is shown in FIG. 4 separated from a segment 4 of therunflat 2. The two eye bolts 28 are provided with threaded fixings 38for fitting into the eye bolt holes 20 of a segment, and the adjusterscrews 30 for adjusting the cables 6 are clearly visible. The barrel nut38 is provided with a threaded hole 40 for receiving the threadedtension rod 44.

FIG. 5 shows a small gearbox assembly 42 from which a pair of threadedtension rods 44 extend. A first end of each tension rod 44 is connectedto a proprietary universal joint 46 which itself is connected to anoutput shaft on each side of the gearbox assembly. The second end ofeach tension rod 44 is free to be attached to the barrel nut 34 within acompensating bracket 32. A taper is provided on the second end of eachthreaded tension rod 44 to ease assembly. The gearbox assembly 42comprises a worm gear which drives a gear fitted on the output shaft.The gearbox assembly 42 additionally comprises four threaded fixings 48for attaching the gearbox assembly 42 to a segment 4 of the runflatdevice 2, as shown in FIG. 6.

FIG. 6 shows two ends of the runflat device 2 being joined together. Thegearbox assembly 42 is mounted on a further separate segment 4′, whichmay or may not be identical to the segments 4 connected together bycables 6 in the remainder of the runflat device 2. The gearbox assembly42 is mounted using the central holes 22, so the eye bolt holes 20 ofsegment 4′ are not used. This is clearly visible in FIG. 6. The tensionrods 44 are shown threaded through the barrel nuts 34 in thecompensating brackets 32 and received in guide channels 36.

In the end of the worm gear is a hexagonal hole 50 into which aproprietary hexagonal tool or Allen key, such as a ball-ended Allen key,may be inserted to turn the worm gear. When the worm gear is turned theoutput shaft on the gearbox 42 turns and in turn rotates the tensionrods 44.

One tension rod 44 and associated barrel nut 34 incorporates aleft-handed thread, and the other tension rod 44 and barrel nut 34incorporate a right-handed thread. When the two tension rods 44 areturned by the gearbox assembly 42 they will either pull the two ends ofthe cables 6 together or force them apart depending on direction ofrotation. The universal joints 46 allow articulation circumferentiallyof the entire string of connected segments 4, and account for changes inthe angle of the tension rods 44 as the circumference of the runflat 2is increased or decreased. The compensating bracket 32 is not directlyfixed to the segment 4, so is able to pivot relative towards or awayfrom the segment 4 about the adjustor screws 30, due to the flexibilityof the cables 6, to account for changes in the angles of the tensionrods 44.

The tension rods 44 are shown in FIG. 6 having been wound most of theway through the barrel nuts 34 to bring the ends of the runflat 2 closetogether. However, the tension rods 44 are of sufficient length so thatwhen just connected to the barrel nuts 34 by one or two threads the twoends of the string of segments 4 are wide enough apart that the overallouter diameter of the runflat insert device 2 fits snugly inside andagainst the inner side of the tyre's tread area, thus filling the outerhalf of the tyre's inner cavity and leaving the lower or inner half ofthe tyre's cavity and sidewalls and the tyre's beads un-obstructed. Thuslocated, the complete runflat device 2 assembly is connected togetherand held in place within the outer diameter inside the tyre and the tyremay be fitted to the wheel rim in the normal fashion using normal tyrefitter's equipment. Significantly, the entire assembly is held withinthe tyre ready for final tightening without obstructing the beads of thetyre, which can be easily fitted on to the wheel in the normal way.

The runflat device 2 of the present invention also advantageouslyprovides a lateral pressure to the beads of a tyre to function as a truebeadlock device. The legs 12 of the individual segments 4 have a degreeof flexibility and are angled outwards from the top plate 10 towardstheir ends 14 where they will seat on the wheel. When not subject to anysupplied force, the segments 4 are dimensioned so that the ends 14 ofthe legs 12 fit reasonably snugly between a tyre's beads when therunflat device 2 is initially tightened down and fitted. As furthercircumferential tension is applied through increased tightening, thesegments 4 are pulled more tightly on to the wheel rim and the legs 12of each segment flex laterally outwards so that the ends 14 of the legs12 of each segment 4 are forced outwards into the tyre's beads. Thislateral pressure applied to the beads of the tyre forces the beads intothe wheel seats to provide a true ‘beadlock’.

When running deflated, the weight of the vehicle is supported by therunflat 2 and this creates a vertical downwards force on the top plate10 of each segment 4 as the wheel revolves. This force pushes eachsegment 4 harder into the wheel on which it locates. This downwardsforce is resisted by the legs 12 of each segment 4 by being transferredinto a sideways or lateral force by the flexibility in the legs 12 andinto the tyre's beads. Thus, the beadlock force generated when runningdeflated is greater than the force already achieved when the tensioncables 6 were initially tightened. This action when running flateffectively provides an active beadlock, where the greater the weight onthe device (and therefore the greater the requirement for beadlockbecomes), the more lateral pressure is applied to the tyre's beads andthe greater the beadlock effect is generated.

The fitting of the combined runflat and beadlock insert device 2 willnow be described. For the purposes of the description, reference is madeto a normal single-piece drop-centre wheel rim 15 and pneumatic tyre.However, the device of the present invention is also suitable forfitting to a number of different wheel and tyre combinations. Similarly,the method described could be applied to devices which lack some of thefeatures of the device described above.

The runflat device 2 is assembled from a string of segments 4 withsleeve 8 fitted to form a single flexible chain. This chain is coiledinto a small enough circle so that it fits within the inner diameter ofa tyre 52 (i.e. the inner diameter formed by the beads of the tyre).This is shown schematically in FIG. 7. FIG. 7 also shows that the sleeve8 extends beyond both ends of the chain of segments. The sleeve 8 islonger than the chain of segments 4 by approximately the length of onefurther segment 4, for reasons which will become apparent. 25 Onceinserted into the tyre 52 cavity, the runflat device 2 is then uncoiledto the maximum available diameter so that it fits snugly against theinside of the tyre's tread area, as shown schematically in FIG. 8.

A further individual segment 4′, identical to the segments 4 making upthe coiled chain, carries the tension rods 44, gearbox assembly 42 andconnecting universal joints 46. With the chain of segments 4 arranged asin FIG. 8, this further segment 4′ is inserted into the tyre cavity andthe free ends of the tension rods 44 are inserted into barrel nuts 34 ateach end of the chain.

If the length of the tension rods 44 is too great to allow fitment whenthe chain of segments 4 is fully extended circumferentially, then thesegment 4′ with gearbox 42 may be pulled inwards, towards the beads ofthe tyre, a small distance. The tension rods 44 may be angled upwardsvia the universal joints 46 such that the distance between the free endsof the tension rods 44 is decreased allowing the tension rods may beinserted in the barrel nuts 34. The compensating brackets 32 can pivotaway from the segment 4 as previously described to receive the ends ofthe threaded tension rods 44. As an alternative, the barrel nut 34 maybe arranged rotated 90° from the illustrated embodiment so that thebarrel nuts 34 can pivot vertically (towards and away from the segments4) rather than horizontally. This simplifies the operation and allowsgreater tightening of the cables 6 prior to this stage to ensure that nosegments 4 are dislocated during fitting. A commonly available‘floating’ cable tensioner can also be provided to apply and equalizethe tension in the cables 6, and this is preferably located opposite thegearbox segment 4′ in order to help balance the weight of the gearbox42.

The input on the gearbox 42 may then be turned using an Allen key toscrew the tension rods 44 into the barrel nuts 34 sufficiently to allowthe segment 4′ with gearbox 42 to be pushed upwards against the insideof the tyre's tread and in line with all the other segments 4 of thechain.

At this stage the sleeve 8 is moved circumferentially round the stringof connected segments 4 or the string of connected segments 4 is movedcircumferentially relative to and within the sleeve 8 so that the twoends of the sleeve 8 are moved away from the area where the segment 4′housing the gearbox 42 is connected. This arrangement, illustrated inFIG. 9, effectively holds the end segments 4 and the gearbox housingsegment 4′ in line with the main body of the string of segments 4 readyfor tightening onto the wheel rim. Because the tension rods 44 are rigidand the segments 4 are pre-tensioned in the chain, the entire runflatdevice 2 can at this stage be expanded, by turning the gearbox inputanticlockwise, and effectively forced against the inside of the tyre'stread area and held in place there while the beads of the tyre 52, whichare unobstructed, are fitted to a wheel. The sleeve 8 in thisarrangement additionally helps to hold the segment 4′ housing thegearbox 42 radially outward so that it does not move towards the wheelcentre as the radius of the runflat device 2 is increased. In the largerview of FIG. 10, a section of the sleeve 8 has been removed toillustrate how the shape of the sleeve effectively wraps around thesides 16 of the top plate 10 of each segment 4,4′ to provide resistanceagainst this inward movement.

The inner bead of the tyre 52 is then fitted to the wheel rim in thenormal way. The gearbox assembly 42 and its worm drive input are thenpositioned adjacent to the valve hole of the wheel.

To act as a guide or a retaining device to aid fitting, a fine cablewith a screw device on one end is loosely attached to the gearboxassembly 42 or the segment 4′ carrying the gearbox assembly 42 and theother end of the cable is passed through the valve hole. This aidsfitting by keeping the worm drive adjacent the valve hole and preventingcircumferential movement of the device 2 within the tyre cavity whenfitting.

A normal metal bolt-on valve is connected inside the tyre cavity andunder the runflat device 2 through the valve hole to a normal tyrefitter's ‘fishing tool’ as used for fitting tubed tyres.

The second or outer bead of the tyre 52 is then fitted to the wheel inthe normal way.

The standard metal valve has as a soft rubber washer at its base. Thevalve is pulled into the valve hole via the ‘fishing tool’ and its outercollar loosely attached in order to provide enough of a seal via therubber washer to allow the tyre fitter to inflate and seat both thetyre's beads. The wire used as a locator to the runflat device 2 withinthe tyre cavity should be sufficiently fine that it can pass around therubber washer at the base of the valve. The tyre is then inflated in thenormal way to seat the tyre beads on the wheel.

The tyre is then deflated and the valve is unscrewed from the valve holeand allowed to drop inside the tyre cavity whilst still being retainedby the wire of the fishing tool through the valve hole. The guide orretaining wire may at this point be used to ensure the worm drive isadjacent the valve hole.

At this point, the complete wheel, tyre 52 and runflat device 2 can bemade to stand vertically, i.e. as it would be run on the vehicle, sothat the runflat device 2 inside the tyre cavity can be more easilypulled into position, i.e. on to the wheel rim between the tyre's beads.Alternatively, the tightening can be performed with the wheel lyingflat. When tightened, the runflat device 2 simply slides up the insideof the tyre's wall and into place on the wheel.

A hexagonal drive tool (preferably a ball ended Allen Key) is theninserted through the valve hole to locate in the hexagonal drive 50 inthe end of the worm gear of the gearbox 42 and used to apply aprescribed torque, which initially draws the entire runflat device 2into position, before applying a further prescribed tension to thetension rods 44 and tension cables 6 in order to pull the segments 4down onto the wheel sufficiently to flex the legs or sides 12 of thesegments 4 and push them laterally into the tyre's beads to provide abeadlock force.

The entire assembly of the runflat device 2 is substantially laterallyrigid, the rigidity of the pre-tensioned segments 4 being complementedby the sleeve 8, so that when the diameter of the assembly is reduced asthe assembly is tightened during fitting the entire assembly can followthe contour of the tyre down and between the tyre's beads withouttwisting and without any individual segments 4 moving out of alignment.The sleeve 8 also covers corners of the individual segments 4,preventing them from catching on the sides or beads of the tyre andindividually twisting or dislocating.

The guide or retaining wire may be unscrewed at this point and pulledout of the valve hole, and the valve pulled into the valve hole fromunder the runflat device 2 with the tyre fitter's proprietary ‘fishingtool’ attached, and secured in position in the normal way. Finally, thetyre is inflated and the wheel balanced as usual.

The invention described above thus provides:

-   -   A combined runflat and beadlock insert device comprising a        plurality of part-annular components or segments already fitted        and tensioned together to allow the entire device to be pulled        down between the tyre's beads without the risk of any        misalignment of any individual components catching on the inside        of the tyre's walls or beads and not seating correctly between        the tyre's beads when finally tightened on to the wheel rim;    -   A mechanism to function so that after the device is located        between the tyre's beads, further tightening or tensioning        forces legs or side parts of the segments outwards and into the        tyre's beads to apply sufficient lateral pressure to the beads        to provide a beadlock;    -   An ‘active beadlock’ function whereby a load applied to the        runflat device during use causes increased lateral pressure on a        tyre's beads; and    -   A construction and method of fitting to allow a single-piece        laterally rigid runflat and beadlock device to be inserted and        held within the tyre cavity so as not to obstruct the tyre's        beads to enable the tyre fitter to fit the tyre to a normal        single-piece drop-centre wheel rim using normal tyre fitting        equipment.

The invention is not considered to be limited to the configurations andmaterials described above. The configuration of the structure as well asthe dimensions and, to a certain extent, the material of the componentparts would be dependent on a specific application.

For example, the segments 4,4′ shown in the application are wide andflat, and are suitable for a low profile road tyre. Similar segments4,4′ for use within an off-road tyre would typically need to be tallerand possibly narrower, but would otherwise share many of the featuresand characteristics described above.

As described, the segments 4,4′ have a common design for ease ofproduction/manufacture. Differing wheel sizes can be accommodated byvarying the number of segments 4 making up the chain. It is howeverconsidered that smaller or larger segments could be provided for usewith very small or very large diameter wheels, or in combination withthe standard segments to account for unusual wheel diameters ifrequired.

1-18. (canceled)
 19. A method of fitting a runflat device comprising aflexible body having two ends, the method comprising the steps of:coiling the flexible body to a diameter smaller than an interiordiameter of a tyre; inserting the coiled body into a cavity of the tyre;uncoiling the body within the tyre cavity and connecting the ends of thebody with an adjustable connection means, thereby forming a ring; andexpanding the ring with the adjustable connection means, therebylocating the ring against an inside of a tread area of the tyre.
 20. Amethod of fitting a runflat device according to claim 19, furthercomprising the step of fitting an outer sleeve to the flexible bodybefore coiling the flexible body.
 21. A method of fitting a runflatdevice according to claim 19, further comprising the step of fitting thetyre to a wheel after expanding the ring, and subsequently tighteningthe adjustable connection means, thereby tightening the ring and locatelocating the runflat device on the wheel in abutment with beads of thetyre.
 22. A method of fitting a runflat device according to claim 21,further comprising the steps of positioning the adjustable connectionmeans adjacent a valve hole in the wheel, and accessing the adjustableconnection means via the valve hole.
 23. A method of fitting a runflatdevice according to claim 22, comprising the additional step of furthertightening the adjustable connection means, thereby deforming theflexible body and forcing parts of the flexible body against the beadsof the tyre.
 24. (canceled)
 25. A method of fitting a runflat deviceaccording to claims 19, wherein the flexible body is formed as a chainof individual segments joined together in abutment with one another, thechain being flexible, and ends of the chain being joined together by theadjustable connection means, which adjusts a distance between the endsof the chain, and thereby forms the ring with the body diameter beingadjustable.